NEW UK DESIGNED & BUILT THEREMIN with volume loop & pitch rod etc

Look forward to hearing your opinions Gordon. Nice chap is John and as you say an intelligent man eh? Nice lot of musical instruments in the 'studio' as well. He made a change to my early LV-3 unit a while back as there was a slight development issue with a variable pot and the germanium diode. Sorted it with no fuss and got it back to me asap. So you (Thomas G and anyone else who has one from now) are benefitting from having the latest upgrade for reliability; as do I now. Nice too to see someone who is not just out to make a few pound sterling/bucks, but enjoys his creations & their owners responses!!!

I received my LV3 theremin a few days ago and have had opportunity to play it a little, and these are my first impressions.

It's built to a price. This was confirmed by the maker, John, who, like ChrisC, I collected my LV3 from. It comes in a stock aluminium enclosure, there is no on/off switch (you unplug the power supply, and/or pull the audio jack out if there is a battery inside), installing a 9 volt battery is not made easy, the thread for fitting it to a microphone stand is tapped into a strip of Perspex (from the look of it) fixed to the base plate and the eye protector on the top of the pitch rod is (I think) one of those plastic caps that covers a screw that has been countersunk into wood. The three control pots are fitted on the underside of the circuit board, which fits exactly in the enclosure and is put in upside down, so the knobs are on the top of the enclosure rather than the side, which is good for left handed players.

Installing the battery requires removing the volume loop, unscrewing four screws and sliding the base plate off the enclosure. The battery holder is on the circuit board.

The thread for fitting to a mike stand is for the smaller of the two standard mike stand fittings. All of my mike stands (except my tabletop mike stand) came with a small screw fitting on the top, and an adaptor ring in place to make it a larger fitting (i.e. the fitting for an etherwave) so this is unlikely to be a problem. The instrument is small and light enough to be supported by a miniature mike stand such as one suitable for miking a kick drum (not a boom) which would be good for tabletop use. Or you could use a tabletop camera tripod with an adaptor ring to convert the thread to fit. Available on Amazon. (It also has four little rubber feet that it can stand on.)

The volume loop is springy and just slots into a couple of holes. On a couple of occasions I have touched it while playing and there was a lot of crackling, but not every time. I think coating the end with a conductive grease might alleviate this. The pitch rod has a screw fitting, and it also easy to fit and remove.

The circuit board looks to remove easily, but casual dismantling is not something I am inclined to do in case I muck it up. Also I think I would need a hex key to dismantle the pitch rod attachment. I like the enclosure, but it looks as if it would be fairly straightforward to put it in a different box. I did not ask John about this possibility, so it would be good to consult with him first. I noticed some trim pots inside, but they are not mentioned in the user manual, so I plan to leave them well alone.

The enclosure is quite small. Nonetheless, by using the far end of the long volume loop I can play with my arms almost of far apart as when I play my etherwave. (I tend to favour the near end of the volume loop.) I usually tune the pitch field so that the full range is available to me. To get a better spread of notes I'll be tuning the LV3 so that I need to step back for the lowest notes (i.e. those lower than a classical repertoire typically calls for) and I'm ok with that.

It takes a while to warm up and the pitch field stabilise. How long will vary according to environmental factors and the player's sensitivity to the geometry of the field and their tendency to compensate for variation subconsciously. Switching it on first and then doing all the other stuff you do before you play, including having a nice cup of tea or whatever you do to get into a relaxed state of mind, is a good idea.

I will defer judgement on the linearity to classical players, but to me it feels pretty much the same to me as the etherwave (with Thierry's extension) except for the three centimetres closest to the rod, where it goes very high very quickly until I can't hear it, and in the very low notes, where it spreads out rather than contracting like my etherwave. And it goes down to about 5Hz (again a guess, I can hear beats on my sub that are slightly faster than I can count in my head).

The volume field has an interesting geometry. With the control knob about half way, moving my hand slowly up from the loop, the volume gets louder, the the timbre gets a bit of distortion and it continues to get louder, then it gets quieter again. Making the field larger will mean you need to step further away before it goes silent, and you will have to raise your hand higher to distort the tone. I imagine classical players will place it above reach. Making the field smaller will mean the distortion kicks in sooner. I have not found a setting that makes the sound distorted all the time, but I can get it very close to the loop. Naturally adjusting the volume field like this will mean that either you will be playing very softly all the time, or very loudly. You can adjust for this with the output volume knob, to turn down loud distorted playing or turn up soft undistorted playing. There is some interplay between the two knobs, the volume field adjustment knob and the output volume knob, so it is not quite as straightforward as that. (I think. The jury is still out on that one.)

I like the undistorted timbre. The sound of a theremin depends a lot on both the player and the amp, but with me playing it through the most neutral amp I could afford (designed for singer songwriters with acoustic guitars and microphones playing small venues) it sounds very clean, and not unlike my etherwave with both waveform and brightness knobs set to about 11 o'clock (exact settings vary from one etherwave to another). I would describe it as a pure, ringing tone, pleasantly richer than a sine wave and without any obtrusive overtones. I think a skilled player could make it sing in the mid-range.

The distorted tone is quite harsh in the mid-range and better suited to the lower register, where it has some oomph. It has a lot of overtones, and seems well suited to filtering, such as with wah and formant filter pedals. (I haven't got to trying that yet, mind you.) The transition from unfiltered to filtered gives a bit of a "sh" or "ch" sound if you move your volume hand quickly through it, but moving very slowly into it gives individual harmonics entering the sound like controlled guitar feedback. It's a small range, so you have to approach it delicately. I have been building up cluster drones on my delay and just sneaking very slightly into the transition zone now and then to add little icy stabs. It's the sort of thing I enjoy doing.

I think this is a worthwhile addition to the budget theremin market, and for less than £100 is value for money. An etherwave costs around £360 in the UK, for comparison, and it is at least half as good an instrument. Its target market includes newcomers wanting to dabble their toes in the water without committing to a major expense and non-classical players. Whether a classical player would want it as a second theremin I will leave for them to decide. Battery power does make it well suited to busking, and the lack of grounding in that situation is probably easiest overcome with an antistatic wrist strap connected to the instrument, although I am sure more elegant solutions could be devised.

I have been told by a Russian contact who bought one, that its essentially an EW. I dont believe this (although it may have some EW similarities?). Of particular interest to me is whether the LV3 has any antenna equalization - Did you notice any inductors or coils which look like they may do this job?

From what you say about the volume antenna operation, it sounds like this is some form of simple clipping / overdrive distortion.. And yes, I can see that this, in combination with a post-VCA (and therefore post distortion) volume control, you can get quite a lot of flexibility.

Not sure I understand the volume getting quieter "the the timbre gets a bit of distortion and it continues to get louder, then it gets quieter again." - This sounds like an incorrectly tuned filter on the volume circuit, increasing the volume as hand capacitance reduces, reaching the top of the curve (at the filters resonant frequency) then reducing as the frequency moves to the other side of the resonant point.

The board does not look much like an etherwave board to me. I can't see the characteristic coils near the pitch rod, or the trim-able inductors. I could be mistaken but I think there are three trim pots. The only component I can see that might be a coil looks like a fat resistor with coloured stripes. The marking on the board suggests it is a number of micro Henrys. (Lower case u with a tail, capital H) Henrys are a measure of inductance, if I recall correctly.

i don't think it is incorrectly tuned. John had it set up when I got there and demonstrated it for me, so I imagine it is as he wants it to be. It means that I can walk away from the theremin without needing to mute it, which is a convenience.

(I'm currently a couple of hundred miles away from my LV3, so this is from memory.)

Without tunable inductors, and without equalizing inductors, its extremely unlikely to be based on the EW! - And yes, uH us micro Henrys.. Its not going to be an equalizing inductance with a value in the uH range - EQ inductors are larger - usually in the mH range.*

As for volume tuning, "incorrect" was with reference to the EW and other theremins operation that I have seen - as in "normal" operation - But there is no reason why "normality" is compulsory - silencing a theremin when the player is away from it is, IMO, a good idea - I do this by muting my theremins when they operate on the wrong side of the pitch null point (when the VFO frequency is >= the reference frequency).

*Have just seen the photo of the board you sent.. looks like a 470uH is connected directly to the pitch antenna - This one thing shows me how this theremin is likely to be operating - And it has NO similarity to the EW in any way !

It actually really surprises me that this theremin works as well as it does, and that it doesnt drift more! - as I see it, the VF oscillator probably operates directly through the 470uH and antenna capacitance, and the reference oscillator through 680uH and its (trimmable) capacitance - circuits are probably close or identical, giving some degree of thermal compensation.. But the frequency determining components are not all identical - in particular, the trim capacitor on the Ref Osc is not duplicated on the VFO.. Trimming capacitors and potentiometers can have severe temperature dependencies.

I expect the operating frequency is quite high, possibly over 1MHz (with normal antenna capacitance and 470uH in series with this, one gets abour 2MHz - there will be other capacitances at play and deliberately added by the tuning circuit, but I would be really surprised if these dropped the frequency below 1MHz or even 1.5MHz).

I have no guess as to the operation of the volume circuit or VCA - this could be quite clever, as there appears to be no inductors - Oh - I see them ! ;-) Ok - no mystery anymore! ;-)

This is probably the cheapest possible design that could be implemented within the price (or perhaps any price, LOL) - John has probably managed to put the absolute minimum system together and people are happy with it! That is quite an achievement IMO!

I think people will like the price, be happy that it exceeds their price-based expectations of it and forgive its deficiencies because of the price. I guess that >£100 puts it at the top end of the impulse purchase range. It did for me. :-)

I was interested to note that a lot of the circuit board is unpopulated. The first reason I thought of which seems plausible is that it started as a more complex design that was then simplified until it was in budget.

"I was interested to note that a lot of the circuit board is unpopulated. The first reason I thought of which seems plausible is that it started as a more complex design that was then simplified until it was in budget." _ GordonC

The size of the PCB is dictated a bit by the box size - its the single most expensive component (or perhaps the case is) even though its the cheapest possible single-sided board, and has lots of spare space.. It costs nothing to add traces/places for extra components, so its always a good idea to pack as much as one might possibly use for a more advanced build, into the available space.

Guessing at the function these missing components could provide, it looks to me like a pair of 3819 (jFet) buffers for the oscillators (or perhaps a jFet mixer), and a switchable capacitance selector, giving 6 positions.. Probably having resistors on thev 'A' connections (?) - Possibly a tone selector switch, with a toggle perhaps to select either the standard (existing) tone or this alternative tone / mixer.

"I was interested to note that a lot of the circuit board is unpopulated. The first reason I thought of which seems plausible is that it started as a more complex design that was then simplified until it was in budget." _ GordonC

The size of the PCB is dictated a bit by the box size - its the single most expensive component (or perhaps the case is) even though its the cheapest possible single-sided board, and has lots of spare space.. It costs nothing to add traces/places for extra components, so its always a good idea to pack as much as one might possibly use for a more advanced build, into the available space.

Guessing at the function these missing components could provide, it looks to me like a pair of 3819 (jFet) buffers for the oscillators (or perhaps a jFet mixer), and a switchable capacitance selector, giving 6 positions.. Probably having resistors on thev 'A' connections (?) - Possibly a tone selector switch, with a toggle perhaps to select either the standard (existing) tone or this alternative tone / mixer.

Fred.

I have a decent picture of the board if you want Fred. I saw there was going to be a rotary switch perhaps for octaves ranges but John (designer) decided against it after trying one as it affected the pitch linearity etc.

One important point about the LV3 that I did not notice at first is that the aluminium enclosure is effectively part of the pitch rod. Moving the pitch hand down, parallel to the rod and over the enclosure, causes a significant rise in pitch.

One important point about the LV3 that I did not notice at first is that the aluminium enclosure is effectively part of the pitch rod. Moving the pitch hand down, parallel to the rod and over the enclosure, causes a significant rise in pitch.

I had to check this as I'd never noticed it, and my LV-3 has a slight pitch decrease when starting at the top of the pitch rod and passing down & parallel to the pitch rod..............but only very slightly. This whether my hand be in the centre over the housing enclosure or nearer the pitch rod. Interesting.

I guess because I try and play 'horizontally' I'd never noticed this effect.